Dynamic Directional Lighting for Surface Defect Inspection
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Solution Overview
Problem
Current defect inspection methods for sheet materials, such as automobile paint jobs, rely on inadequate lighting solutions that fail to effectively highlight surface defects, leading to inefficiencies in both manual and automated inspection processes.
Innovation Solution
A defect inspection system utilizing an array of light sources forming a plane with a range of illumination directions covering at least 90 degrees, where the light sources operate in a sequence to provide maximum intensity from a single direction, which changes over time, enhancing shadow contrast and facilitating defect detection through directional lighting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light sources illuminate the sample from all directions simultaneously, then the sample surface is well-lit, but defect visibility is reduced due to lack of shadow contrast
Solution Approach 1:
The lighting system is segmented into multiple independent light sources arranged in an array, allowing individual control of each light source. This enables selective illumination from different directions rather than simultaneous omnidirectional lighting, creating shadow contrast that highlights surface defects while maintaining adequate overall illumination.
Solution Approach 2:
The lighting system dynamically changes illumination patterns by sequentially activating different light sources or groups of light sources. This dynamic switching creates time-varying shadow patterns that reveal defects, while the system maintains appropriate illumination levels throughout the sequence, resolving the contradiction between adequate lighting and defect visibility.
2Difficulty of detecting and measuring
If a single light source illuminates the sample, then shadow contrast is maximized for defect detection, but the range of detectable defect orientations is limited
Solution Approach 1:
The array of light sources provides multi-functionality by enabling illumination from multiple different directions sequentially. Each light source can be activated to create shadow contrast for specific defect orientations, and by cycling through different light sources, the system achieves universal coverage for detecting defects with various orientations while maintaining the shadow contrast benefits of single-direction illumination.
Solution Approach 2:
The system employs periodic action by cyclically activating different light sources in the array. This periodic switching allows the system to systematically cover different illumination angles, ensuring that defects with various orientations are detected at appropriate intervals in the cycle, thereby achieving comprehensive defect orientation coverage while preserving shadow contrast.
3Device complexity
If the lighting system is simplified to a single source, then device complexity is reduced, but defect detection accuracy decreases
Solution Approach 1:
The array of light sources is designed to be controlled in a sequential or selective manner, where not all light sources need to operate simultaneously. This self-service approach allows the system to achieve high defect detection accuracy by activating only the necessary subset of light sources for each inspection phase, thereby maintaining detection precision while avoiding the full complexity of simultaneously managing all light sources.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves defect visibility and detection accuracy by creating dynamic lighting conditions that highlight shadow changes, making it easier for both manual and automated systems to identify surface defects, thereby reducing the need for extensive repair processes and enhancing inspection efficiency.
Implementation Method 1
Each point of the sample is illuminated in a sequence with a maximum light source intensity in a single incident direction... creating dynamic lighting conditions that highlight shadow changes
Data Source
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Figure 2(a)~2(b)
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AI summary
A defect inspection system is provided for inspection of defects in the surface of a sample. An array of light sources is used, with different light sources providing light to the sample from different directions. A main direction of illumination is defined with highest intensity, and this direction evolves over time. By providing varying directional illumination instead of blanket illumination, it becomes easier to detect defects.